JPH0326816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to the production of photosensitive semi-conductors in which, after exposure to light, the metal can be deposited from a metal ion solution in the form of nuclei which are enhanced by physical development or by an electroless plating solution. The present invention relates to a method for forming a metal image or pattern on at least one of the top and bottom surfaces of a substrate containing a conductive compound or a substrate made of the compound.

Prior Art U.S. Pat. No. 3,380,823 discloses such a method of forming images on a medium comprising a paper support provided with a layer of semiconducting pigment in a polymeric resin binder. In this method, the pigment is reversibly activated by exposure through the image negative, and the medium is then contacted with an image-forming reduction-oxidation system, thereby irreversibly forming an image.

A corresponding method for forming conductive metal patterns on insulating polymeric substrate materials, such as printed circuit boards, is described in U.S. Pat. No. 3,674,485;
This method also uses a substrate material on the surface of which a layer is formed by uniformly dispersing a photosensitive semiconductive metal compound in a hydrophobic resin binder. In this method, a pattern of metal nuclei is formed by selective exposure and contact with a solution of the relevant metal ions, and the image of the metal nuclei is then enhanced with a physical developer or an electroless plating solution to form a conductive pattern. form.

These methods require the use of screen patterns or, in some cases, negatives. Also, maintaining selectivity during formation of the nuclear image and its intensification requires additional processing, such as the use of antifogging means.

OBJECTS OF THE INVENTION The present invention aims at making the use of these measures and guarding patterns superfluous and significantly simplifying the formation of the image or, as the case may be, the formation of the pattern.

Structure of the Invention The present invention provides the steps of: immersing the surface of the substrate, in which the photosensitive semiconductive metal compound is present inside or on the surface, in a solution containing ions of a nucleating metal;
then patternwise exposure by a focused beam of laser light moving in a controlled manner relative to said substrate and having a wavelength in the ultraviolet or visible part of the spectrum such that it is absorbed by said associated semiconducting compound. It is characterized by

First, metal nuclei are photochemically deposited from such a solution onto a surface portion that contains a semiconducting compound and is incident on the laser beam. Image metal can then be deposited on this catalytic nuclear image by electroless deposition without further exposure. In this case, there is no need to keep the substrate immersed in the same bath.

Exposure can be performed by moving the light beam according to a desired pattern using known programming techniques.

In another embodiment of the invention, the exposure is carried out in a solution of a metal salt suitable for electroless plating or physical development and a reducing agent for the metal salt.

Special Publication No. 50-92830 (CA 84 , 94240n (1976)
) discloses a method for depositing gold patterns on Ga--As surfaces. However, to do this they primarily use CO ₂ -lasers which generate radiation at a wavelength of 10 μm. In this wavelength range, photochemical processes such as those carried out in the method of the invention are of course not possible. The metal deposits described in these publications must be the result of thermal effects.

Instead of using a guard pattern, the nucleation needs to be sufficiently rapid to allow working with methods that use radiation with a controlled light beam that moves relative to the substrate according to the pattern to be formed. There is. This requires that the semiconducting metal compound used in the method of the invention be sufficiently photosensitized to allow, in conjunction with the intensity of the laser beam used, very short exposure times. . Furthermore, it is necessary that the solution in which the surface is immersed has a sufficiently high degree of transparency for the light used.

Highly suitable semiconducting metal oxides within the scope of the invention are titanium dioxide or zinc oxide.

Nucleating solutions in which gold or gold alloys can be deposited electrolessly, taking into account the requirement that the solution of ions of the nucleating metal must have the highest possible transparency to the light used. It is of great interest to use it for the formation and subsequent reinforcement of the nucleus. These solutions, which are disclosed in Dutch Patent Application No. 8103174 and British Patent No. 1322203, have significantly higher transparency than, for example, electroless copper plating solutions in the wavelength range suitable for photosensitive semiconductors. Only the last-mentioned solutions are suitable for use in the process of the invention at relatively low concentrations or with shorter optical paths through the solution.

Next, the present invention will be explained with reference to examples.

Example 1 A substrate material comprising a 4% by weight of titanium dioxide particles (rutile type) dispersed in a glass fiber reinforced epoxy resin was treated with a methyl ethyl ketone-water (1:2) mixture for 6 minutes at 50°C, and then While exposing this to vibrations with a frequency of 50Hz for 6 minutes,
Per: 120 g of Na ₂ Cr ₂ O ₇ made hydrophobic by treatment with a solution containing 400 ml of H ₂ SO ₄ (d=1.84) and 200 ml of H ₃ PO ₄ (d=1.88) and water.

Thereafter, the substrate material is washed in water and then mixed with the following composition per unit: Copper sulfate 0.04 mol Tetrasodium salt of ethylenediaminetetraacetic acid
A quartz cuvette was placed in a 50° C. aqueous solution containing 0.072 mol NaOH, 0.12 mol formaldehyde, and 0.10 mol formaldehyde.

The substrate material was then exposed to a focused beam of a pulsed nitrogen laser in the solution. This laser has a power output of 1 MW, a wavelength of 337 nm, and a pulse duration of
The pulse frequency was 4 ns and the pulse frequency was 10 Hz. The light path through the solution was kept to a minimum. The effective exposure time was 12×10 ^-8 seconds, and a clear image was obtained after 10 minutes of intensification.

Comparable results were obtained using ZnO powder dispersed in epoxy-glass fiber material.

Example 3 A substrate material loaded with titanium dioxide was prepared after a similar pre-treatment step per: tetrasodium salt of ethylenediaminetetraacetic acid.
It was placed in an aqueous solution containing 0.072 mol NaOH 0.12 mol potassium gold() cyanide 0.014 mol and heated to 50°C.

This sheet material was exposed to a pulsed nitrogen laser similar to that used in Example 1. One pulse with an effective exposure time of 4 x 10 ^-9 seconds was sufficient to obtain a clear visible image.

Example 3 A plate filled with titanium dioxide pigment was made hydrophobic in the same manner as in Example 1, then placed in an electroless copper plating solution similar to Example 1, and heated with an argon ion laser (output approximately 0.70 W, wavelength 334351 and 364nm)
was exposed continuously for 16 seconds. During exposure, this plate is exposed for about 7
It was moved in a straight line over a distance of mm. After being left in the solution for about 10 minutes after exposure, a copper line with good conductivity was obtained.

Example 4 Each plate was filled with TiO ₂ pigment and pretreated as in Example 1: PdCl ₂ 5.6×10 ⁻³ mol HCl 0.12 mol and “Tensagex DP24”, i.e. alkylaryl It was placed in an aqueous solution containing 0.4% by weight of a wetting agent consisting of polyglycol ether sulfate.

This plate was exposed to light at 1,1/2 using the argon ion laser of Example 3 (output approximately 0.70W).
The exposure times ranged from 1/4, 1/8, 1/16, 1/32, and 1/64 seconds. After remaining in the copper plating solution heated to 50° C. for about 1 minute, a black image was obtained on the exposed plate at all exposure times.

Example 5 A plate made of Al ₂ O ₃ ceramic was mixed with 25% by weight of acetylacetone titanium and 75% by weight of propanol-2.
and then gradually removed from this solution. After drying using a hair dryer, the plate was maintained at 500° C. for 8 minutes and then titanium dioxide was formed on the Al ₂ O ₃ substrate by pyrolysis. Then per plate: Potassium gold() cyanide 0.014 mol Copper sulfate 0.005 mol Tetrasodium salt of ethylenediaminetetraacetic acid
It was placed in a cuvette containing an aqueous solution containing 0.072 mol NaOH 0.12 mol and formaldehyde 0.13 mol.

This plate was exposed for the same exposure time range as in Example 4. A proper visible metal image was formed after 15 minutes in the solution after exposure.

Claims (1)

[Claims] 1. A photosensitive semiconducting compound capable of depositing this metal from a metal ion solution in the form of nuclei after exposure by physical development or by an electroless plating solution is present inside or In forming a metal image or metal pattern on at least one side of the surface of the substrate material existing on the surface or the substrate material made of the compound, the photosensitive semiconductive compound is added inside or on the surface. is present on the substrate surface in a solution containing ions of the nucleating metal, which then move in a controlled manner relative to the substrate and are absorbed by the associated semiconducting compound. 1. A method for forming a metal image or pattern, which comprises exposing according to the pattern to a focused beam of laser light having a wavelength in the ultraviolet or visible part of the spectrum. 2. A method according to claim 1, wherein the exposure is carried out in a solution of a metal salt suitable for electroless plating or physical development and a reducing agent for this metal salt. 3. The method according to claim 1 or 2, wherein the photosensitive semiconductive compound is titanium dioxide or zinc oxide. 4. The method according to any one of claims 1 to 3, wherein an electroless solution for depositing gold or a gold alloy is used for the formation of nuclei and the reinforcement of subsequent nuclei.